Scientists from The University of Western Australian and University ofCambridge have discovered that crinoids, marine creatures from the class ofanimals that includes starfish and sea urchins, survived the Jurassic era byclinging to floating logs and large rafts that allowed them to travel vastdistances across the ocean.

Understanding how crinoids survived on these rafts in Jurassic times hasremained a mystery up until now. It is understood they survived much longer inthe Jurassic period, compared to modern day, but just how they achieved thishas baffled scientists.

The research team examined crinoid fossils from German museums and collectionsand used a spatial analysis to examine fossil positioning to understand theirabundancy, size, distribution and growth patterns.

Adjunct Research Fellow Aaron Hunter from UWA’s School of Earth Sciences saidcrinoids were in a precarious position in ancient times when oceans wereshallower and they faced more predators such as crabs and fish.

“We found that floating logs that could stay afloat for months or years becameessential for their survival in the otherwise uninhabitable shallow seas ofwhat is now England and Germany,” Dr Hunter said.

“We also developed a diffusion model to look at how long a wood log survivedas a means of transport and shelter for the creatures, before it would sink.We found some colonies could last longer than 20 years.”

Dr Hunter said adapting to this way of life allowed the crinoids to avoidpredators and they could also access food found on the surface of the ocean.

“Raft colonies still exist today where plants and animals use objects in theocean as a means of transportation. It explains how remote islands such asHawaii were colonised by flora and fauna,” he said.

Dr Hunter said the findings offered insight into the use of floating logs andrafts today by plants and animals that were normally hard to observe due tothe vastness of the ocean.

“This is a common means of transport and has been observed in situations suchas after the Japanese 2011 Tōhoku earthquake and tsunami, when plants andanimals rafted from Japan to the coast of North America,” he said.

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